1. Field of the Invention
The invention relates to a process of producing electrically conductive or non-conductive layers for improved adhesion of luminescent materials on flat or uni-directionally bent substrates for color picture screens and image display device screens.
2. Prior Art
In order to attain a relatively long life span for luminescent image screens, good adhesion of the luminescent materials to the glass screen substrate is required. Further, it is desirable to treat the relatively soft glass surface on the side facing the phosphor or luminescent materials so as to reduce gas-ion eruptions during bombardment of such surface with electrons. It is also desirable to provide a conductive sub-layer on the glass surface which faces the luminescent materials so that electrical discharge can occur via such sub-layer and thereby prevent an electrostatic charge build-up on the glass substrate.
It is known to add water glass (K.sub.2 SiO.sub.3) to luminescent material compositions and apply the resultant mixture to glass screen substrates and thereby attain improved adhesion of the luminescent materials to the glass screen while simultaneously attaining an increased cohesiveness of the luminescent material layer per se. With such a process, after a curing or tempering process, the individual luminescent material particles are connected with one another as well as with the glass substrate by a thin alkaline glass layer. It is also known to temper or harden glass screens by vapor depositing or sputtering silicon dioxide onto a surface of a glass screen.
Processes for producing patterned luminescent material layers for TV picture tubes or the like is known. For example, German Offenlegungsschrift No. 2,540,132 (which substantially correspondes to U.S. Pat. No. (4,020,191) discloses one such process whereby the luminescent material pattern is provided by a combination of printing and photographic techniques. In this process, the luminescent materials are mixed with light-sensitive materials and glass powder, applied to the glass surface, exposed, developed and then fused to the glass surface.